Tar sands bitumen froth treatment

ABSTRACT

A METHOD FOR TREATING TAR SANDS BITUMEN FROTH WHEREIN THE FROTH IS TREATED IN AT LEAST ONE CYCLONE ZONE AFTER WHICH IT IS TREATED IN AT LEAST TWO CENTRIFUGE ZONES, THEREBY SEPARATING FROM THE FROTH AT LEAS WATER AND SOLID MINERAL PARTICLES AND LEAVING A BITUMEN PRODUCT FOR FURTHER PROCESSING.

April 30, 1974 R, H, SWTH' v 3,803,120

' TAR SANDS BITUMEN FROTH- TREATMENT I Filed July 1975 2 Sheets-Sheet 1'D/LUENT B/TUMEN D/LUENT 6 PRODUC/ FIRST 11 CYCLONE THIRD FEED CENTR/FUGEB/TUMEN ZONE 2 ZONE UNDERFLOW- nFROTH FIRST SECOND UNDERFLOW UNDERFLOWFIG. 7

PRODUCT.

THIRD FIRST {UNDERFLO 23 CENTR/FUGE g I CYCLONE FEED N 2/. SECOND 3 VUNDERFLOW D/LUENT FIG. 2

D/LUENT FIRST UNDERFLOW FIG. 5 52 41 April 30, 1974 Filed July 1973D/LUENT FIRST CE N TR/F U GE ZONE CYCLONE R. H. SMITH TAR SANDS BITUMENFROTH TREATMENT 2 Sheets-Sheet 2 Rooucr SECOND CENTRI- F UGE ZONE THIRDCENTR/FUGE ZONE FIG. 4

FIRST CENTR/FUGE ZONE A FIRST CENTR/FUGE ZONE B- FIG. 6

46 SECOND CENTRI- FUGE T ZONE 47 SECOND CENTRI- FUGE ZOAVE 45 UnitedStates Patent O 3,808,120 TAR SANDS BITUMEN FROTH TREATMENT Robert H.Smith, Richardson, Tex., assignor to Atlantic Richfield Company, LosAngeles, Calif. Filed July 9, 1973, Ser. No. 377,239 Int. Cl. C10g 1/04U.S. Cl. 208-11 12 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THEINVENTION This invention relates to an improvement in the separation ofat least water and solid particles from the froth produced in a hotWater process for separating bitumen from bituminous tar sands.

The froth from this hot Water process generally contains from about 35to about 45 weight percent water and from about to about weight percentsolid mineral particles (coarse and fine) before any dilution. The watercontent of this froth is normally reduced to from about 4 to about 6weight percent and the particles to from about 1 to about 2, weightpercent to produce a bitumen product suitable for further processing.This reduction of water and solids can be accomplished by a plural stagecentrifuging system which uses mechanical centrifuges operated bypowerful motors to create a strong centrifugal force to separate waterand solid particles, and diluent if present and different from water,from the bitumen froth.

In such a system the first stages of centrifuging are conducted by theapplication of relatively low forces to remove coarse mineral particles,e.g., greater than about 5 microns in size, while relatively higherforces are applied in the later stages of centrifugation to remove finemineral particles, e.g., generally equal to or less than 5 microns insize, and most of the water. The particles and water discharged from thecentrifuges are removed from the system and are treated for theseparation therefrom of any diluent present (if different from water)and for disposal.

In this invention, reference to particle size means the diameter of theparticle if it is essentially round or the largest cross-sectionaldimension of the particle if it is not essentially round.

Thus, heretofore, separation of water and particles has been achieved inits entirety by the use of large expensive centrifuges which require alarge amount of energy input as well as capital expense. Suchcentrifuges include discnozzle centrifuges, solid-bowl centrifuges, andthe like, and are normally employed in the industry to remove solidsfrom liquids.

SUMMARY OF THE INVENTION According to this invention, part of thecentrifuges heretofore used in the treatment of tar sands froth areeliminated thereby providing a substantial savings in capital expenseand operating expense. This is accomplished by subjecting the froth,upstream of any centrifuging zone, to at least one cyclone settling zonein which the froth is tangentially injected into the cyclone zone sothat it moves in a circular manner as it also moves downwardly under theforce of gravity thereby using a centrifugal force, which is notmechanically generated as with centrifuges, to amplify the settling rateof solids and water p CC from the froth. Cyclones are not in theindustry considered to be centrifuges, for example, see Unit Operationsof Chemical Engineering, by McCabe and Smith, McGraw-Hill Book Company,Inc., New York, 1956, page 394. Also, although it is known to usecyclones in the separation of solids from liquids, cyclones are normallyused to remove solid particles or liquid drops from gases.

In this way, substantial amounts of the more easily separated water andsolid particles, particularly coarse particles, are removed by cyclonesettling prior to treatment in centrifuging zones thereby decreasing thevolume of material which the centrifuging zones must operate on. Thisallows the use of smaller numbers and/or smaller sizes of centrifuges ineach centrifuging zone as hereinafter described.

This invention also provides a method for reducing bitumen losses by theuse of countercurrent washing of cyclone underflows with diluent whichis lower boiling than bitumen. Bitumen is thus replaced by the diluentwhich can be recovered by distillation.

Accordingly, it is an object of this invention to provide a new andimproved method for treating tar sands bitumen froth. It is anotherobject to provide a new and improved method for separating solidparticles from bitumen froth. It is another object to provide a new andimproved method for treating a bitumen froth prior to centrifuging ofsame. It is another object to provide a new and improved method forremoving water, solid particles, and diluent if any, from a bitumenfroth. It is another object to reduce bitumen losses.

Other aspects, objects and advantages of this invention will be apparentto those skilled in the art from this disclosure and the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows one embodiment withinthis invention wherein a cyclone settling zone precedes first and secondcentrifuging zones.

FIG. 2 shows another embodiment within this invention wherein aplurality of cyclone settling zones precedes first and secondcentrifuging zones.

FIG. 3 shows another embodiment within this invention wherein a cyclonesettling zone precedes three centrifuging zones.

FIG. 4 shows an embodiment within this invention wherein a plurality offirst and second centrifuging zones are employed in lieu of single firstand second centrifuging zones as shown in FIGS. 1 and 2.

FIG. 5 shows an embodiment within this invention wherein a plurality ofcentrifuges are employed as can be done in any of the centrifuging zonesshown for FIGS. 1 through 4.

-FIG. 6 shows a simplified form of a cyclone separator.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 shows a feed bitumen frothpassing by way of pipe 1 into cyclone settling zone 2. The frothcontains bitumen, water, coarse and fine mineral particles, diluent ifdifferent from water (e.g., a hydrocarbon diluent such as naphtha).Diluent is added by way of pipe 3. Cyclone zone 2 separates out from thefroth some particles, particularlycoarse particles, and some water toproduce a first underflow in pipe 4. The underflow is removed from thefroth thereby creating a bitumen enriched material which remains and isremoved by way of pipe 5 as a first overhead. Diluent may or may not beadded to this first overhead by way of pipe 6. There can be one or morecyclone zones 2 and each zone can contain one or more cyclone devices asdesired. Thus, a substantial amount of relatively easily removablesolids and water is settled from the froth feed prior to passing thatfroth into any centrifuge zone. This way the bitumen enriched materialin pipe 5 is already reduced in materials to be separated so that firstcentrifuge zone 7 which feeds on material in pipe 5 can be sized andoperated to more efficiently remove a certain class of materials such asremaining coarse particles and some water. The particles and water, andany diluent if present, are removed in a second underflow by way of pipe8 thereby forming a bitumen rich overhead which is removed as secondoverhead in pipe 9 and passes as feed to a second centrifuge zone 10.

There can be one or more first centrifuge zones 7 and each can containone or more centrifuge machines. Preferably, first zone 7 removes mostof the remaining coarse particles and is a centrifuge of the solid-bowlor scrolltype.

Second centrifuge zone 10 is preferably designed to remove a substantialamount of the remaining fine particles and a substantial amount of waterand therefore can employ centrifuges of the disc-nozzle type. As withzone 7, there can be one or more zones 10 and each zone can contain oneor more centrifuges. Zone 10 removes a substantial amount of water andfine particles, and possibly some residual coarse particles and diluentif any, from the process by way of pipe 11 thereby leaving a bitumenproduct as the overhead from zone 10. This product is removed separatelyby way of pipe 12 from the third underflow in pipe 11 for furtherprocessing as desired.

FIG. 2 shows a modification within this invention wherein three cyclonezones A, B, and C are employed in series so that the underflow from zoneA in pipe 20 is employed as feed for zone B and the underflow from zoneB in pipe 21 is employed as feed for zone C, diluent being added to pipe21 by way of pipe 22 if desired. The overhead from zone A is passed byway of pipe 23 as feed for first centrifuge zone 7. The overhead fromzone B is returned as at least part of the feed for zone A by way ofpipe 24. The overhead from zone C is returned by way of pipe 25 as atleast part of the feed for zone B. The second underflow from first zone7 is passed by way of pipe 26 to be combined with the first underflowfrom zone C in pipe 27 and these combined underflows pass by way of pipe28 to be combined with the third underflow in pipe 11 to produce a finalcombined underflow in pipe 29 which is removed from the process anddisposed of as desired. Again, each of cyclone settling zones A throughC can contain one or more cyclone settlers hooked in series in the samemanner as the series hookup shown for zone A through C of this FIG. 2.

This configuration of cyclone zones provides a method of countercurrentwashing to reduce the loss of bitumen in the tailings stream 29. At eachcyclone stage, except the last, the feed is mixed with the overflowstream from the succeeding cyclone zone. Fresh diluent is added to thefeed to the last cyclone zone. The overflow streamwhich is combined witheach feed has a lower bitumen content than the feed. As a result, mostof the bitumen is dissolved in diluent and removed in the overflow ofthe liquid cyclone. The bitumen content in the underflow from each zoneis therefore lower than that from the preceding zone. Bitumen in thefeed to each zone is replaced by diluent in the underflow, and thediluent can be easily recovered by distillation and the like.

FIG. 3 shows apparatus similar to that of FIG. 1 except that a thirdcentrifuge zone 30 is employed to operate on the underflow 31 from firstcentrifuge zone 7. Diluent may or may not be added to the underflow fromzone 7 by way of pipe 32. The underflow from third zone 30 is removed byway of pipe 33, e.g., combined with the underflow in pipe 4 for jointdisposal. The fourth underflow in pipe 33 will contain yet additionalamounts of water, particles, and diluent if any, and the more purifiedmaterial remaining in third zone 7 is removed as overhead therefrom byway of pipe 34 for further treatment in second centrifuge zone 10. Thus,in this embodiment, part of the valuable bitumen in the underflow inpipe 31 is reclaimed by third centrifuge zone and returned to theprocess by way of pipe 34. Since zone 30 is employed as a cleanup zone,part or all of the third underflow in pipe 11 can be returned by way ofpipe 35 as at least part of the feed for zone 30 thereby reclaimingresidual bitumen from the third underflow in pipe 11 for return to theprocess by way of pipe 34. Any part of the third underflow in pipe 11not returned by way of pipe 35 to zone 30 is removed from the system byway of pipe 36.

FIG. 4 shows an alternative which can be employed in any of FIGS. 1through 3 or any other embodiments within this invention wherein aplurality of first centrifuge zones and/or a plurality of secondcentrifuge zones are employed. In this figure the overflow from acyclone zone such as pipe 5 of FIGS. 1 and 3, pipe 23 of FIG. 2, and thelike, is represented as a feed for first centrifuge zone A in pipe 40 ofFIG. 4. Zone A produces an underflow in pipe 41 and an overflow in pipe42. Overflow 42 is used as feed for first centrifuge zone B which inturn produces an underflow in pipe 43 and an overflow in pipe 44. Theoverflow in pipe 44 is used as feed for second centrifuge zone A whichproduces an underflow in pipe 45 and an overflow in pipe 46. O'verfiow46 is used as feed for second centrifuge zone b which produces anunderflow in pipe 47 and a bitumen product in pipe 48.

,FIG. 5 shows a series coupling of two centrifuge machines which issimilar to the series coupling of cyclone zones A through C in FIG. 2.The series coupling of two or more centrifuge machines as shown in FIG.5 can be employed in any centrifuge zone shown in FIGS. 1 through 4. Forexample, taking the apparatus of FIG. 5 as that which is within firstcentrifuge zone A of FIG. 4, the feed to the first centrifuge 50 is inpipe 40. Centrifuge 50 produces an overflow which is passed into pipe 42for transmittal to first centrifuge zone B of FIG. 4, and also producesan underflow in pipe 52 which is passed to the second centrifuge 53 inzone A. Centrifuge 50 produces an underflow in pipe 41, which is theunder-flow for zone A as shown in FIG. 4, and an overflow in pipe 55which is returned as at least part of the feed for centrifuge 50. Thissort of series hookup with two or more machines can also be employed infirst centrifuge zone B, second centrifuge zone A, and/or secondcentrifuge zone B, of FIG. 4. Similar reasoning also applies to theother centrifuge zones in FIGS. 1 through 3.

FIG. '6 shows a simplified apparatus for a cyclone device wherein thefroth feed 60 passes into the cyclone at the top of a spiral chamber 61so that as the froth moves downwardly under the force of gravity somecentrifugal force is applied to the froth to amplify the settling rateof the solids and water from the froth. Therefore, at the bottom ofchamber 61, by use of a physical divider 62, a stream of water andsolids 63 is removed separately from the bitumen enriched stream 64.Other known cyclone devices can be employed, for example, thosedisclosed starting at page 366 of Unit Operations of ChemicalEngineering, supra.

Example Bitumen froth feed composed of 63 weight percent bitumen, 9weight percent solid particles (coarse and fine), 28 weight percentwater, all weight percents being based on the total weight of the feed,is treated in the system shown in FIG. 1 wherein naphtha diluent isadded to the froth and passed first through a cyclone settling zone 2produce a first underflow 4 containing, based on the first underflow, 51weight percent coarse particles, 6 weight percent bitumen, 3 weightpercent naphtha and the remainder water. The bitumen enriched overheadin pipe 5 passes into a scroll-type centrifuge which constitutes firstcentrifuge zone 7 and hich produces a second underflow 8 which contains,based on the second underfiow, 63 weight percent coarse solids, 4 weightpercent bitumen, 2 weight percent naphtha, and the remainder water. Thebitumen rich overhead from zone 7 is then passed to second centrifugezone which contains a disc-nozzle centrifuge and which produces a thirdunderflow 9 containing, based on the third underflow, 6 weight percentfine particles, 2 weight percent bitumen, 1 weight percent naphtha andthe remainder water. The bitumen product in the overhead from secondcentrifuge zone 10 contains, based on the bitumen product, 60 weightpercent bitumen, 36 weight percent naphtha, 0.6 weight percent solidmineral particles (coarse and fine) and 3 weight percent water, allweight percents being based on the total weight of the overhead in pipe12.

By use of cyclone settling zone 2, a single centrifuge machine of modestsize is employed in each of zones 7 and 10 the desired degree of removalof water and solids from the bitumen froth still obtained.

Reasonable variations and modifications are possible within the scope ofthis disclosure without departing from the spirit and scope of thisinvention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows.

1. A method for treating a tar sands bitumen froth which includesbitumen, water, coarse mineral particles, and fine mineral particles toseparate substantial amounts of at least water and coarse and fineparticles from the bitumen comprising passing said froth through atleast one cyclone settling zone to remove a first underflow whichincludes water and coarse particles and to leave a bitumen enrichedfirst overflow, passing said first overflow through at least one firstcentrifuging zone to remove a second underfiow which includes additionalwater and coarse particles and to leave a second bitumen rich overflow,passing said second overflow through at least one second centrifuge zoneto remove a third underfiow which includes water and fine particles andto leave a bitumen product, and removing said bitumen product separatefrom said third underflow.

2. A method according to claim 1 wherein a hydrocarbon diluent is addedto the process upstream of said cyclone zone, upstream of said firstcentrifuge zone, or upstream of both said zones.

3. A method according to claim 1 wherein at least two cyclones areemployed in each cyclone zone, said zones being employed in series sothat the overflow from any cyclone subsequent to the first cyclone inthe series is recycled as at least part of the feed for the nextpreceding cyclone.

4. A method according to claim 3 wherein the underflow from the lastcyclone of said series is removed from the process.

5. A method according to claim 3 wherein diluent is added to the feed ofthe first cyclone in said series, to the feed of the last cyclone insaid series, or to both such feeds.

6. A method according to claim 1 wherein each first centrifuge zoneemploys at least one solid bowl centrifuge and each second centrifugezone employs at least one discnozzle centrifuge.

7. A method according to claim 1 wherein there is employed at least onethird centrifuge zone, the feed for said third centrifuge zone beingsaid second underflow, the overflow from said third centrifuge zonebeing employed at least in part as feed for said second centrifuge zone,the underfiow from said third centrifuge zone being removed from theprocess.

8. A method according to claim 7 wherein diluent is added to the feed ofsaid cyclone zone, the feed of said third centrifuge zone, or both saidfeeds.

9. A method according to claim 7 wherein the underflow from said secondcentrifuge zone is at least in part returned as at least part of thefeed to said third centrifuge zone.

10. A method according to claim 7 wherein at least two cyclones areemployed in each cyclone zone, said cyclones being employed in series sothat the overflow from any cyclone subsequent to the first cyclone inthe series is recycled as at least part of the feed for the nextpreceding cyclone.

11. A method according to claim 10 wherein the underflow from the lastcyclone of said series is removed from the process.

12. A method according to claim 10 wherein diluent is added to the feedof the first cyclone in said series, to the feed of the last cyclone insaid series, or to both such feeds.

References Cited UNITED STATES PATENTS 3,338,814 8/1967 Given et al.20811 3,558,469 1/1971 White et a1. 20811 3,607,720 9/1971 Paulson 20811CURTIS R. DAVIS, Primary Examiner

